This invention relates to a brake assembly for a motor vehicle.
One type of brake system for a vehicle has a rotor that rotates with a wheel of the vehicle. To brake the vehicle, brake pads are applied to each side of the rotor, thereby creating friction to slow movement of the rotor. The brake pads are moved into contact with the rotor by a brake actuator driven by a heavy hydraulic or pneumatic cylinder. The cylinder itself requires lines, connectors and other components that significantly add to the overall weight and cost of such a brake system. While such a system can apply strong braking forces quickly to the rotor, the system is heavy and expensive to produce.
Recently, manufacturers have sought to develop electrical braking systems that brake the vehicle through electrical motors linked to the brake pads. Such systems eliminate the need for the hydraulic or pneumatic cylinder, lines, connectors and related components of traditional systems. Electric braking systems also permit greater control over braking because they may be easily linked with computer controllers. However, the forces necessary to slow a vehicle are large, particularly for commercial vehicles. As a consequence, a high torque output electric motor is generally required for these systems.
High torque output electric motors are expensive and consume a large amount of electricity from the vehicle's electrical system. Moreover, while high torque electric motors provide sufficient braking force, they are generally slow turning motors. A slow turning motor may cause an undesirable delay in brake actuation.
A need therefore exists for an improved brake assembly and method that provides the benefits of an electric braking system without the excessive expense, energy consumption, or delay associated with a high torque electric motor.